Philip J. Silva
Assistant Professor
Analytical Chemistry
(435) 797-8192 psilva@cc.usu.edu
Our research is focused on the development and application of methods for the analysis of small particles. In the atmosphere, aerosol particles arise from many different sources, including wind-blown dust, vehicle exhaust emissions, and condensation of gas-phase compounds in the atmosphere. These particles impact both the local and global environment, affecting human health, visibility, and climate change. Standard methods of analyses, such as gas chromatography, leave a significant fraction of the particle chemical composition unidentified. In our group, we employ mass spectrometry to detect chemical species and understand their origin in particles.
A main project is the continued development and application of real-time mass spectrometry for aerosol analysis. Real-time mass spectrometry allows for on-line, quantitative determination of many organic and inorganic components of aerosol particles. In addition, the size of particles can be determined by combining the mass spectrometer with an appropriate technique from aerosol science. We currently utilize an aerosol mass spectrometer (AMS) for real-time analysis of particles. The AMS has a rapid time response to detect transient changes in the atmospheric or laboratory aerosol. We also are investigating matrix-assisted laser desorption/ionization (MALDI) as a technique for particle analysis. Many of the compounds present in aerosols are large, non-volatile species. These compounds are difficult to detect with most chemical analysis methods. MALDI has been used by many groups for analyses of organic compounds, such as proteins, that are difficult to volatilize. Similarly, we want to use MALDI for analysis of particulate phase compounds that are difficult to volatilize.
A strong program in aerosol research requires both field and laboratory
measurements. Field measurements ensure that the chemical systems one
studies in the laboratory are relevant to what is happening in the atmosphere,
while laboratory measurements allow one to study a chemical system under
controlled conditions. The field of aerosol chemistry is extremely
broad, so projects are limited only by one’s imagination. A few of
the research projects we are currently focused on are the characterization
of particle emissions from combustion sources, the photochemical oxidation
of gas-phase hydrocarbons to dicarboxylic acids, and the analysis of indoor
air particles. The experimental work in this group is primarily analytical
chemistry, but our work overlaps with physical, atmospheric, and environmental
chemistry.
Selected Publications
P. L. Tanaka, D. D. Riemer, S. Chang, G. Yarwood, E. C. McDonald-Buller, E. C. Apel, J. J. Orlando, P. J. Silva, J. L. Jimenez, M. R. Canagaratna, J. D. Neece, C. B. Mullins, and D. T. Allen “Direct Evidence for Chlorine-Enhanced Urban Ozone Formation in Houston, TX,” Atmospheric Environment, (2003), 37, 1393-1400.
P. J. Silva and K. A. Prather “Interpretation of Mass Spectra from Organic Compounds in Aerosol Time-of-Flight Mass Spectrometry,” Analytical Chemistry , (2000), 72, 3553-3562.
D. S. Gross, M. E. Gälli, P. J. Silva, S. H. Wood, D.-Y. Liu, and K. A. Prather “Single Particle Characterization of Automobile and Diesel Truck Emissions in the Caldecott Tunnel,” Aerosol Science and Technology , (2000), 32, 152-163.
P. J. Silva, R. A. Carlin, and K. A. Prather “Single Particle Analysis of Suspended Soil Dust from Southern California,” Atmospheric Environment , (2000), 34, 1811-1820.
P. J. Silva, D.-Y. Liu, C. A. Noble, and K. A. Prather “Size and Chemical Characterization of Individual Particles Resulting from Biomass Burning of Local Southern California Species,” Environmental Science and Technology , (1999), 33, 3068-3076.
P. J. Silva and K. A. Prather “On-Line Characterization of Individual Particles from Automobile Emissions,” Environmental Science and Technology, (1997), 31, 3074-3080.
For more information about the Silva research group, follow these links:
Silva Group Home Page
Full Publication List
Group Links Page
This page was last updated:
August 25, 2004
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